Instead of hardcoding the differences between UMAC scans and LMAC
scans (which in this case is the number of simultaneous scans that can
run), introduce a max_scans variable and stop scans of the other type
(i.e. stop sched scan if regular scan is being attempted and
vice-versa) if the number of running scans reached the maximum.

Add a function that checks if the maximum number of scans was reached
and stops the appropriate scan to make room for the new scan.
Signed-off-by: NLuciano Coelho <luciano.coelho@intel.com>
Reviewed-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NEmmanuel Grumbach <emmanuel.grumbach@intel.com>